Process of laying concrete pavements.



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FRANKLIN S.- LAMSON, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSICrNOR TO COSMOS CONSTRUCTION COMPANY, INC.,

OF WASHINGTON, DISTRICT OF COLUMBIA,

A CORPORATION OF THE DISTRICT OF COLUMBIA.

PROCESS OF LAYING CONCRETE PAVEMENTS.

Specification of Letters Patent.

Patented Nov. to. 1909.

No Drawing. Original application filed August 14, 1902, Serial No. 119,673. Divided and this application filed June 25, 1903, Serial No. 163,043. Renewed March 6, 1907. Serial No. 360,884.

To all whom it may concern:

Be it known that I, FRANKLIN S. LAMSON, a citizen of the United States, residing at Washington, District of Columbia, have discovered a new and useful Process of Laying Concrete Pavements, of which the following is a specification.

This discovery relates to the laying of that class of concrete pavements in which the concrete is formed of Portland cement as the binding materialf'i'fl cbiiibinatio sand avel crushed-stone and water, and it as or its ofiectthfifitfdction of such pavements by the use of such a process and such appliances as will give to the plastic mass, formed by the combination of the material above named, such rigidity as will enable it to be forced from the mixing machine, through openings of desired form, in a compressed continuous mass of form-retaining consistency which will permit it to be received upon conveyers, cut to desired lengths, carried to the prepared bed, there to be laid at once in the desired number of layers, compressed at one operation, blanketed to protect from injury, and further compressed during the period of the setting of the cement; completing the pavement in one series of operations.

As stated in my application filed Aug. 14:, 1902Serial No. 119,673, (patented Nov. 5, 1907, No. 870,370) of which matter herein formed part, I have discovered that when the combination of such materials, in proper proportions and properly worked, is made with the temperature of the materials at about the expansion decreasing-temperature of water 39 to,32 f li, it gives sufiicient rigidity to flie plastic product to enable the performance of all the operations named in the above statement as to object; thereby giving opportunity to use machines whereby great rapidity and accuracy are obtainable, both in the preparation of the material and the performance of the worksince the product (of regular size), after being forced out of the machine and cut to lengths, can

be conveyed directly to the workmen, and evenly laid and rolled while fresh 2'. e. before the cement sets, thus making the pavement a homogeneous mass of even quality and ature the initial and final settings of the cement are retarded (varying in extent with the brands used) so that sufiicient time is given for the completion of the work described, without injury to the product from premature setting.

In the practical application of this process, the grading should be accurately done, so that the regular thickness of material may produce a surface of regular contour (although inaccuracies may .be corrected by the application of loose material, of similar quality and temperature, during the rolling process); a layer of non-conducting and non-absorbent material should then be laidto prevent the absorption, by the earth, of water from the concrete, and as a non-conductor of heatupon Which the layer, or layers, of concrete blocks should be regularly and closely placed, and thoroughly rolled to the correct contour. By the use of two or more machinesor of one machine having two or more mixing and forcing chambers-two or more layers of differing quality (such as a base and a surface) can be laid, and by one rolling operation the mass can be united and compacted before the setting of the cement. After rolling, and before the setting of the cement, when desired, the surface of the pavement can be scored, indented or otherwise roughened (to prevent slip in wet or frosty Weather), by the use of properly prepared rollers, or other tools. Should it occur that concrete block! be reduced to too low a temperature, and their surfaces become partially frozen, the roller compression would crush together and equalize them, and the cement not having set no injury would be done. During the period of initial. and final setting the pavement should be blanketed with non-conducting material, to prevent absorption of heat and consequent injury; and heavily loaded, as by having the machinery and material used in the work moved forward upon it as the work progresses, in order to continue the compression during such period.

From the above description it will be seen that the mixed material receives compression first, in being forced fromthe mixing chamber; second, in the rolling which unites and endurance. At the above-named temper- .compacts the layers of blocks of fresh maafri XL} f i i the cement.

terial; third, in having the rolled pavement loaded during the period of the setting of The sequences in the process are: First, the mixing of the material at the stated temperature; second, forcing it into concrete form; third, separating it into sections; fourth, conveying the sections to the place of deposit; fifth, placing the sections in layers on the prepared bed; sixth, rolling the layers to contour; seventh, covering, and compressing, the pavement during the setting period. The initial period of setting varies, from two to three hours; the final period, from six to seven hours, or more.

In the construction of the street pavement the blocks, or sections, are laid in layers from curb to curb; the roller, or rollers, compress to contour, working forward at the properdistance from the block-layers; the blanketing and compressing pavement-cover (of Wood, or metal, with the under surface covered with non-conducting material)accurately made, in sections convenient for handlingis laid to cover the rolled pavement, following the completed rolling process closely (and after the entire set of cover-sections is in use, passing the rear sections consecutively to the front), and the cover heavily loaded to continue the compression; as the rear sections are carried to the front and laid the compression-load is moved forward upon them; the whole operation thus moving forward continuously day and night when desired. It is evident that in this additional-compression process it is necessary to place a suitable cover on the :freshly-rolled pavement to support the adjustable load, and its weight combined with that of the adjustable load forms the full compression-load. In order to facilitate the forward movement, and adjustment, of the compression-load upon the said pavement-cover, each section thereof can be provided with car-tracks which would properly connect with those of its adjoining sections, so that trucks containing desired portions of such load may be moved thereon at will. The graduated automatic movement of this load, to correspond with the forward progress of the work, may be made by a suitable connection with the operative motive'power of the plant. A part of the car-tracks which may be placed upon the said cover may be used for the purpose of transporting the separate sections from the rear to the front thereof, as the work progresses; still other tracks may be laid on which to transport the concrete blocks from the mixing machine, located on the finished pavement in the rear, to the workmen at the front. XVhen desired the lower surface of the said pavement-cover may be provided with projecting strips, or pieces, of any desired form, size, arrangement, or material, whereby indentations or grooves may be made upon the surface of the pavement. Each section of the pavementcover should be detachably connected to each adjoining section in such manner as to cause the product-ion of a finished contour of the pavement, free from ridges, lumps, and hollows.

The mixing machine and motive-power may be placed in any desired position relative to the front line of the pavement being laid; and the delivery of the freshly made concrete sections to the workmen may be made by endless conveyer, truck, barrow, or hand labor, as desired.

In the construction of floors, or covers, over arch, vault, or other openings, beneath or in pavements, sidewalks, bridges, etc., metal rods, bars, lath, netting, expanded sheets, etc., may be used in combination with the concrete material; the method of such combination may be varied, adapted to condition and circumstance, one such method being the introduction of such strengthening material between layers of concrete, which, when united by compression and becoming set, would form the homogeneous strengthened mass desired.

The object of the final compression of the series is the production of continued increased pressure during the setting periodas compared with the temporary roller-compression, whereby added density, and consequent hardness, is given to the product. The weight of the compression-cover, and load, will operate to force the scoring or indenting strips or pieces (which are preferably of metal, and strongly fastened to the cover) into the surface of the freshly-rolled pavement, and a V-section shape of such strips will facilitate their entrance into the concrete, and by their wedge form aid in giving the pressure desired. The non-conducting blanketing material should also be non-absorbent of water, in order to not extract the water required in the proper chemical combination and crystallization in the formation of the concrete stone; such material, in these respects, being similar to that on which the concrete is laid.

In arranging the compression-load upon the pavement-cover care should be taken to so place the loaded trucks as to equalize the pressure over the surface covered; having been so arranged, and connected by proper mechanism to form a simultaneously operative system, the entire system of loaded trucks may, by suitable clock-workor otherdevices, be so moved by the motivepower of the plant as to give an automatic movement forward thereto, so graduated as to correspond with the forward movement of the work. From the block-forming machines to the block-laying workmen the blocks may be brought by endless belt, or chain, conveyers, capable of proper speed adjust ment, so as to synchronize with the other IIVIIV,

.'--v-j --v-v| van-"I176 $5 l operations; the position ofsucn machines the material with its temperature at about 65 should be such as best to aid the progress of 39 to 32 F giving the plastic mass conthe work. crete forms of varied figuresuch as curb- The edges of the pavement-cover sections forms, gutterforms and main pavement 5 may be provided with coordinating metal forms, and emplacing them while fresh in a mortise-and-tenon plates, detachable hinge pavement construction.

joints, and bolt-and-socket devices, whereby 2. The process of Portland concrete paveaccuracy of surface contour and quickness ment construction which consists in mixing of adjustment may be produced; such secthe material with its temperature at about tions may also be so arranged as to have each 39 to 32 F., giving the plastic mass concoursefrom curb to curb break joints crete forms of varied figure, emplacing them with each adjoining course, whereby the While fresh in a pavement construction, and entire set of sections, when fastened toby rolling pressure bringing them to correct gether, will form a mutually strengthened contour.

whole; when, however, it may be preferable 3. The process of making Portland consuch courses of pavement-cover (as well as crete pavement which consists in mixing the the layers of pavement blocks) may be laid, material with its temperature at about 39 in sections, lengthwise of the street instead to 32 F., giving the plastic mass concrete of transversely. forms of regular size, laying them while When the pavement-blocks are laid in two fresh upon a prepared bed, and rolling them or more layers, each superposed layer should to the correct contour while still fresh. break joints with its adjoining layer below, 4:. The process of making Portland conboth longitudinally and transversely; in crete pavement which consists in mixing the order to accomplish this result the initial material with its temperature at about 39 block in each such layer (also each final to 32 F., giving the plastic mass concrete block) should be cut to proper length; and forms of regular size, laying them while this may be done by the block-layer (since fresh upon a prepared bed, rolling them to the blocks are yet of operative consistency), the correct contour while still fresh, and or such blocks may be halved before delivery blanketing the rolled pavement with non to the block-layer; also, each consecutive conducting material while the cement sets.

layer (from curb to curb) should break 5. The process of making Portland conjoints with each preceding layer, so that the crete pavement which consists in mixing the subsequent compression may the more thormaterial with its temperature at about 39 oughly unite and compact the plastic blocks to 32 F giving the plastic mass concrete 35 of concrete into a pavement formed of a forms of regular size, laying them while monolithic mass of stone. fresh on a prepared bed, rolling them to the In order to insure the completion of the correct contourwhile still fresh, and subseprocess before the initial setting of the quently applying to the rolled pavement cement takes place, when desired, the secadditional pressure during the period of the tions of the pavement-cover may be made setting of the cement, to impart additional to a pattern so as to be interchangeable, in density and hardness to the pavement. which case the metal section-connecting de- 6. In a process for compressing the plastic vices (mortise plates, hingeplates, boltmaterial of a concrete pavement, the step of sockets, etc.) should be so constructed as to rolling said material to contoursueh rollallow some lateral variation, at the same ing giving temporary compression, and the time retaining (vertically) the accuracy of step of providing a pavement-cover-emthe surface-contour of the sect-ions, thereby placed upon said rolled pavement, and placadapting to practical application the theo-. ing upon said cover a continued-compresretical requirement, and making allowance Sion load, whereby continued, and addifor slight possible variation. tional, pressure may be given to such pave- In the construction of such pavements menttheir curb-form and gutter-form sections 7 In a process for compressing the plastic may be emplaced in advance of the rest of material of a concrete pavement which conthe pavement, or simultaneousl with it; or sists in a temporar roller-compression, and

the main pavement and gutterorm sections a continued, or ad itional, compression, the

may be emplaced in advance and the curb step of adjusting said continued, or addisections superposed, but in such case the tional, compression-load upon its supporting placement of the plastic curb-sections should pavement-coveras by means of car-tracks closely follow that of the sub-sections in and trucks, whereby the pressure of said order that the compression may unite them load may be equalized.

while both are plastic. 8. In a process for compressing the plastic I claim: material of a concrete pavement which con- 1. The process of Portland concrete pavesists in a temporar roller-compression, and ment construction which consists in mixing a continued, or ad itional, compression, the

step of automatically moving forward said continued, or additional, compression-load in synchrony with the prior steps in the process.

9. In a process for compressing the plastic material of a concrete pavement, laying an extended, extensible, load-supporting cover on the surface of a freshly-rolled pavement, placing an equalized load on said cover, and 

